Porphyromonas gingivalis, Treponema denticola, and Tannerella forsythia exist in a polymicrobial biofilm associated with chronic periodontitis. The aim of this study was to culture these three species as a polymicrobial biofilm and to determine proteins important for bacterial interactions. In a flow cell all three species attached and grew as a biofilm; however, after 90 h of culture P. gingivalis and T. denticola were closely associated and dominated the polymicrobial biofilm. For comparison, planktonic cultures of P. gingivalis and T. denticola were grown separately in continuous culture. Whole cell lysates were subjected to SDS-PAGE, followed by in-gel proteolytic H2 16O/H2 18O labeling. From two replicates, 135 and 174 P. gingivalis proteins and 134 and 194 T. denticola proteins were quantified by LC–MALDI TOF/TOF MS. The results suggest a change of strategy in iron acquisition by P. gingivalis due to large increases in the abundance of HusA and HusB in the polymicrobial biofilm while HmuY and other iron/haem transport systems decreased. Significant changes in the abundance of peptidases and enzymes involved in glutamate and glycine catabolism suggest syntrophy. These data indicate an intimate association between P. gingivalis and T. denticola in a biofilm that may play a role in disease pathogenesis.

In this study, the essential oils of Orthosiphon stamineus Benth and Ficus deltoidea Jack were evaluated for their antibacterial activity against invasive oral pathogens, namely Enterococcus faecalis, Streptococcus mutans, Streptococcus mitis, Streptococcus salivarius, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Fusobacterium nucleatum. Chemical composition of the oils was analyzed using gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The antibacterial activity of the oils and their major constituents were investigated using the broth microdilution method (minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC)). Susceptibility test, anti-adhesion, anti-biofilm, checkerboard and time-kill assays were also carried out. Physiological changes of the bacterial cells after exposure to the oils were observed under the field emission scanning electron microscope (FESEM). O. stamineus and F. deltoidea oils mainly consisted of sesquiterpenoids (44.6% and 60.9%, respectively), and β-caryophyllene was the most abundant compound in both oils (26.3% and 36.3%, respectively). Other compounds present in O. stamineus were α-humulene (5.1%) and eugenol (8.1%), while α-humulene (5.5%) and germacrene D (7.7%) were dominant in F. deltoidea. The oils of both plants showed moderate to strong inhibition against all tested bacteria with MIC and MBC values ranging 0.63–2.5 mg/mL. However, none showed any inhibition on monospecies biofilms. The time-kill assay showed that combination of both oils with amoxicillin at concentrations of 1× and 2× MIC values demonstrated additive antibacterial effect. The FESEM study showed that both oils produced significant alterations on the cells of Gram-negative bacteria as they became pleomorphic and lysed. In conclusion, the study indicated that the oils of O. stamineus and F. deltoidea possessed moderate to strong antibacterial properties against the seven strains pathogenic oral bacteria and may have caused disturbances of membrane structure or cell wall of the bacteria.

Melicope glabra (Blume) T. G. Hartley from the Rutaceae family is one of the richest sources of plant secondary metabolites, including coumarins and flavanoids. This study investigates the free radical scavenging and antibacterial activities of M. glabra and its isolated compounds. M. glabra ethyl acetate and methanol extracts were prepared using the cold maceration technique. The isolation of compounds was performed with column chromatography. The free radical scavenging activity of the extracts and isolated compounds were evaluated based on their oxygen radical absorbance capacity (ORAC) activities. The extracts and compounds were also subjected to antibacterial evaluation using bio-autographic and minimal inhibitory concentration (MIC) techniques against two oral pathogens, Enterococcus faecalis and Streptococcus mutans. Isolation of phytoconstituents from ethyl acetate extract successfully yielded quercetin 3, 5, 3’-trimethyl ether (1) and kumatakenin (2), while the isolation of the methanol extract resulted in scoparone (3), 6, 7, 8-trimethoxycoumarin (4), marmesin (5), glabranin (6), umbelliferone (7), scopoletin (8), and sesamin (9). The study is the first to isolate compound (1) from Rutaceae plants, and also the first to report the isolation of compounds (2–5) from M. glabra. The ORAC evaluation showed that the methanol extract is stronger than the ethyl acetate extract, while umbelliferone (7) exhibited the highest ORAC value of 24 965 μmolTE/g followed by glabranin (6), sesamin (9) and scopoletin (8). Ethyl acetate extract showed stronger antibacterial activity towards E. faecalis and S. mutans than the methanol extract with MIC values of 4166.7 ± 1443.4 μg/ml and 8303.3 ± 360.8 μg/ml respectively. Ethyl acetate extract inhibited E. faecalis growth, as shown by the lowest optical density value of 0.046 at a concentration of 5.0 mg/mL with a percentage inhibition of 95%. Among the isolated compounds tested, umbelliferone (7) and sesamin (9) exhibited promising antibacterial activity against S. mutans with both exhibiting MIC values of 208.3 ± 90.6 μg/ml. Findings from this study suggests M. glabra as a natural source of potent antioxidant and antibacterial agents.

Abstract:The study aimed to determine the in-vitro anti-bacterial effect of cinnamon (Cinnamomum zeylanicum Blume) oil on pathogenic oral bacteria. Essential oil from cinnamon tree bark was extracted using steam distillation technique and analysed using gas chromatography (GC) and gas chromatography -mass spectrometry (GC-MS). Broth microdilution test was used to determine the Minimal Inhibitory Concentration (MIC) of oil against major oral pathogens in caries and periodontal diseases viz. Streptococcus mutans, S. mitis, S. salivarius, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Fusobacterium nucleatum. Bacterial cell membrane modification following exposure to the oil was observed using scanning electron microscopy (SEM). Through the GC/GC-MS analysis, cinnamaldehyde was identified as the major component of cinnamon oil (82.5% in relative amount). Both cinnamon oil and cinnamaldehyde showed antibacterial activity against the tested bacteria (MIC 0.21 -0.63 mg/mL and 0.8 -0.15 mg/mL respectively). Cell membrane changes were observed following 2h exposure to the oil. This finding suggests cinnamon bark oil as a potential therapeutic agent in preventing bacterial-related oral diseases.

The study aimed to determine the in-vitro anti-bacterial effect of cinnamon (Cinnamomum zeylanicum Blume) oil on pathogenic oral bacteria. Essential oil from cinnamon tree bark was extracted using steam distillation technique and analysed using gas chromatography (GC) and gas chromatography -mass spectrometry (GC-MS). Broth microdilution test was used to determine the Minimal Inhibitory Concentration (MIC) of oil against major oral pathogens in caries and periodontal diseases viz. Streptococcus mutans, S. mitis, S.salivarius, Enterococcus faecalis, Porphyromonas gingivalis and Fusobacterium nucleatum. Bacterial cell membrane modification following exposure to the oil was also observed using scanning electron microscopic (SEM). Through the GC/GC-MS analysis, Eugenol was identified as the major component of cinnamon oil (82.5% relative amount). Both, cinnamon oil and eugenol showed antibacterial activity against the tested bacteria (MIC 0.21 -0.63 mg/mL and 0.8 -0.15 mg/mL respectively). Membrane cell changes were observed following 2h exposure to the oil. This finding suggests cinnamon bark oil as a potential therapeutic agent in preventing bacterial-related oral diseases.